A sealing material composition which comprises, as a base, an organic polymer having a reactive silyl group and is excellent in weatherability is disclosed in Japanese Patent Application Laid-Open (JP-A) No. 5-287186. In the sealing material composition described in this prior art, 0.3 to 3 parts by weight of each of a benzotriazole type ultraviolet absorber and a hindered phenol type antioxidant are blended per 100 parts by weight of an organic polymer having a reactive silyl group.
However, about the weatherability obtained by curing the sealing material composition, the limit value thereof is about 2,000 hours as a value measured with a sunshine weatherometer. Accordingly, in the case that the sealing material is used in outdoor-exposed portions, such as roof structures or outer wall structures, a sufficient weatherability cannot be obtained.
With a rise in the performance of housing, flame retardancy is more intensely desired in sealing materials, for example, sealing materials used in joints of outer walls. In the case that a halogen type flame retardant which is ordinarily used is incorporated into a sealing material, the flame retardancy thereof is enhanced but contamination may be generated by the bleeding-out of the flame retardant or harmful gas may be generated when a fire breaks out.
There is known a method of incorporating, into a sealing material, a compound containing crystal water in the molecular structure thereof, such as magnesium hydroxide, as a flame retardant. However, the incorporated amount thereof is restrictive from the viewpoint of workability. Accordingly, a sufficient flame retardancy cannot be exhibited.
Hitherto, about curable compositions used in sealing materials or the like, a curable composition having a sufficient adhesiveness to an adhesion-undergoing article which cannot be easily adhered, such as a vinyl chloride steel plate or a fluorine-containing resin steel plate, has been intensely desired.